A passenger service unit (PSU) is a unit provided on a vehicle that allows interaction between the vehicle's service providers and passengers, and provides necessary hardware/software for providing various passenger services. In an aircraft, this unit is typically located above a passenger's seat. In general, it is desirable to make PSUs highly functional, yet at the same time, keeping them simple, inexpensive, and lightweight.
The PSU on an aircraft typically includes lighting components (e.g., overhead reading lamps, etc.), emergency oxygen components (e.g., oxygen tank, drop-down masks, etc.), and crew communication components (e.g., cabin attendant button, light-up communication icons such as keep seatbelt fastened and no smoking, a speaker for in-flight verbal communications from pilot and crew. Etc.). Each of these three component sets is typically designed by a separate group of engineers, possibly by a separate organization, and requires its individual power supply and communication feeds. These redundant components increase the weight of the PSU, the complexity of install, the footprint of the install, and the overall cost of the PSU.